While scientists have known about the Earth’s chorus for a number of years, this is really the first time that these unique clicks and whistles have been recorded for the public. The RBSPs captured five separate occurrences of the phenomenon on September 5 using their in-built Electric and Magnetic Field Instrument Suite. The recordings were then made by a team from the University of Iowa and NASA’s Goddard Space Flight Center. However that is not the probe’s main objective – they are to release a pair of satellites that will investigate the various particles that make up the planet’s radiation belts.

Speaking to NPR, Craig Kletzing from the University of Iowa said that the interaction between the sun’s particles and the Earth’s magnetic field produces radio waves that just happen to be in the same frequency range as sounds we can hear.

“We’ve known about this phenomena for a long, long time,” Kletzing said. “I think people first were observing this back maybe even on the ground in the ’50s. But the understanding of exactly how it’s generated still remains one of the key scientific questions for this mission.”